The general problem of maintaining tape, such as magnetic tape, along a desired path, while minimizing transverse tension and edge forces is described in the introduction to U.S. Pat. No. 4,335,857. In summary, it is difficult to maintain vertical tape registration relative to a base over a tape path extending from a supply reel to a transducer and then to a take-up reel. Guides which are interposed along the tape path tend to contact tape edges of vertically misaligned tape, causing fatigue of the tape binder material and creating oxide debris which accumulates on the tape, causing data errors.
Part of the problem of tape misalignment from a vertical plane can be traced to supply and take-up reels. Such reels are sometimes mounted on pins which are slightly tilted with respect to the perpendicular angle from a planar base plate. Such tilted pins cause the tape reel to be similarly tilted, possible causing tape misalignment along the tape path. In addition, when the extremeties of the shaft become worn, the reel will wobble to a greater and greater extent. An object of the invention was to correct reel alignment and hence tape alignment.